The present invention relates generally to an improved coupling device for connecting a towed vehicle, such as a trailer, with a towing vehicle, such as an automobile or truck. More particularly, the present invention relates to a coupling device that includes a cushion assembly for dampening shocks and vibrations in the vertical direction. Preferably, the present coupling device also includes an adjustment assembly for adjusting the height of a ball hitch connector so that the ball hitch connector can be placed at the appropriate level for towing a variety of different types of trailers.
One problem with many simple trailer hitch devices of the prior art is that they do not include any shock dampening mechanism. Without shock dampening, the forces and vibrations created by irregularities in the road surface, changes in acceleration, or a variety of other sources are freely transferred between the towing vehicle and the trailer. These shocks create undue wear and tear on the hitch assembly, and can also be felt as slight "jolts" by occupants of the towing vehicle.
In the prior art, there are currently two general types of coupling devices with some form of vertical cushioning--a first type in which the ball hitch connector is supported on a cushioning structure of an H-shaped configuration and a second type which includes only a single vertically-extending cushion assembly, but in which the connecting component (i.e., a ball hitch connector or a corresponding component such as a socket) is free to pivot about a pivot point. There are drawbacks to each of these two general types.
Examples of the first type of prior art coupling device (of the H-shaped configuration) are disclosed in U.S. Pat. No. 3,708,183 to Jones; U.S. Pat. No. 4,148,498 to Taylor, Jr.; and U.S. Pat. No. 4,215,876 to Jacks (hereinafter the Jones patent, the Taylor patent, and the Jacks patent, respectively). In both the Jones patent and the Taylor patent, the ball hitch connector is attached to a horizontally-extending beam that is supported on each of its edges by a vertically-extending cushioning structure. Thus, when these coupling devices of the first type are viewed from the rear of the towing vehicle, the horizontally-extending beam and the two vertically-extending cushioning structures define the previously mentioned H-shaped configuration. In both the Jones device and the Taylor device, the vertically-extending cushioning structures each include at least a pair of springs that sandwich and support the horizontally-extending beam.
The H-shaped configuration of the Jacks patent is defined by a horizontally-extending leaf spring, which is connected at its edges to two vertically-extending support strips. In the Jacks device, the ball hitch connector is seated on the center of the leaf spring, and each of the support strips includes a number of horizontally aligned holes that enable the vertical position of the ball hitch connector to be adjusted. While the ball hitch connector of the Jacks device is at least partially supported by the leaf spring, the primary means of maintaining the ball hitch connector in position is provided by a slider, upon which the ball hitch connector is affixed, and which is in turn seated within two vertical tracks that enable the slider to slide in the vertical direction.
While the prior art coupling devices with the H-shaped configuration do provide a level of vertical shock dampening, there are several drawbacks associated with these types of coupling devices. One drawback is that these prior art devices are somewhat complex assemblies formed from a relatively large number of parts. One reason for the large number of components is that each of these coupling devices requires a duplicate of each of the parts used in the vertically extending portion, in addition to the rest of the components required. The complexity of the assembly and the number of parts makes these prior art devices somewhat expensive. An additional factor adding to the overall cost of coupling devices of this type is the large number of components that need to be custom manufactured specifically for use in these devices.
Further, these prior art coupling devices are also quite large, and therefore necessitate the allotment of a substantial amount of space at the rear of the towing vehicle. Besides the unsightliness of such large devices, their large size may also contribute to reduced gas mileage from the added wind resistance and their excess weight.
The second type of coupling device with vertical energy dampening is exemplified by U.S. Pat. No. 4,351,542 to Lovell et al. In devices of this type, a horizontally extending "tongue" (upon which is seated the ball hitch connector or the associated socket) is pivotally attached to a bolt that extends horizontally through a housing at a right angle to the tongue. The tongue pivots with respect to the bolt, and is dampened by dampening members positioned above and below the tongue. Thus, the end of the tongue, which carries the ball hitch connector or socket, travels through an arcuate path during the dampening function.
One of the drawbacks associated with this second type of coupling device is related to the arcuate path of the ball hitch connector or socket member. This arcuate path creates unnecessary bending moments and stress concentrations on the tongue and at the area of connection between the ball hitch connector and the socket. Accordingly, these components are subject to undue wear at the points of contact. In addition, the bending moments may create force vectors that weaken the ball hitch connector, which could possibly lead to premature failure of this component.
Accordingly, in response to the drawbacks discussed above, a primary object of the present invention is to provide an improved coupling device for coupling a towing vehicle with a towed vehicle which eliminates the drawbacks of the prior art devices.
More specifically, one object of the present invention is to supply an improved coupling device of relatively simple, inexpensive construction that provides adequate energy dampening.
A related object of the present invention is to provide an improved energy dampening coupling device that may be manufactured in a cost effective manner by relying primarily upon components that can be produced from readily available stock materials, instead of requiring custom manufacture of specialized components.
An additional object of the present invention is to provide an energy dampening coupling device of an improved design that has a relatively small overall size.
A further object of the present invention is to supply an improved coupling device that does not require portions of the assembly to travel through an arcuate path, and therefore eliminates the unnecessary wear and stresses associated with such travel.
Yet another object of the present invention is to provide an improved energy dampening coupling device of simple construction that is adjustable to accommodate trailers of different heights.